MCDwarf: Refactor line table handling into a single data structure

This replaces several "compile unit ID -> thing" mappings in favor of
one mapping from CUID to the whole line table structure (files,
directories, and lines).

This is another step along the way to refactoring out reusable
components of line table handling for use when generating debug_line.dwo
for fission type units.

Also, might be a good basis to fold some of this handling down into
MCStreamers to avoid the special case of "One line table when doing asm
printing, line table per CU otherwise" by building it into the different
MCStreamer implementations.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203821 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/MC/MCContext.h

@@ -108,9 +108,7 @@ namespace llvm {
     /// We now emit a line table for each compile unit. To reduce the prologue
     /// size of each line table, the files and directories used by each compile
     /// unit are separated.
-    typedef std::map<unsigned, SmallVector<MCDwarfFile *, 4> > MCDwarfFilesMap;
-    MCDwarfFilesMap MCDwarfFilesCUMap;
-    std::map<unsigned, SmallVector<StringRef, 4> > MCDwarfDirsCUMap;
+    std::map<unsigned, MCDwarfFileTable> MCDwarfFileTablesCUMap;
 
     /// The current dwarf line information from the last dwarf .loc directive.
     MCDwarfLoc CurrentDwarfLoc;
@@ -146,13 +144,8 @@ namespace llvm {
     /// Darwin).
     bool AllowTemporaryLabels;
 
-    /// The dwarf line information from the .loc directives for the sections
-    /// with assembled machine instructions have after seeing .loc directives.
-    std::map<unsigned, MCLineSection> MCLineSections;
     /// The Compile Unit ID that we are currently processing.
     unsigned DwarfCompileUnitID;
-    /// The line table start symbol for each Compile Unit.
-    DenseMap<unsigned, MCSymbol *> MCLineTableSymbols;
 
     void *MachOUniquingMap, *ELFUniquingMap, *COFFUniquingMap;
 
@@ -298,26 +291,38 @@ namespace llvm {
 
     bool hasDwarfFiles() const {
       // Traverse MCDwarfFilesCUMap and check whether each entry is empty.
-      MCDwarfFilesMap::const_iterator MapB, MapE;
-      for (MapB = MCDwarfFilesCUMap.begin(), MapE = MCDwarfFilesCUMap.end();
-           MapB != MapE; MapB++)
-        if (!MapB->second.empty())
+      for (const auto &FileTable : MCDwarfFileTablesCUMap)
+        if (!FileTable.second.getMCDwarfFiles().empty())
            return true;
       return false;
     }
 
-    const SmallVectorImpl<MCDwarfFile *> &getMCDwarfFiles(unsigned CUID = 0) {
-      return MCDwarfFilesCUMap[CUID];
-    }
-    const SmallVectorImpl<StringRef> &getMCDwarfDirs(unsigned CUID = 0) {
-      return MCDwarfDirsCUMap[CUID];
+    const std::map<unsigned, MCDwarfFileTable> &getMCDwarfFileTables() const {
+      return MCDwarfFileTablesCUMap;
     }
 
-    const std::map<unsigned, MCLineSection> &getMCLineSections() const {
-      return MCLineSections;
+    MCDwarfFileTable &getMCDwarfFileTable(unsigned CUID) {
+      return MCDwarfFileTablesCUMap[CUID];
     }
-    std::map<unsigned, MCLineSection> &getMCLineSections() {
-      return MCLineSections;
+
+    const MCDwarfFileTable &getMCDwarfFileTable(unsigned CUID) const {
+      auto I = MCDwarfFileTablesCUMap.find(CUID);
+      assert(I != MCDwarfFileTablesCUMap.end());
+      return I->second;
+    }
+
+    const SmallVectorImpl<MCDwarfFile *> &getMCDwarfFiles(unsigned CUID = 0) {
+      return getMCDwarfFileTable(CUID).getMCDwarfFiles();
+    }
+    const SmallVectorImpl<StringRef> &getMCDwarfDirs(unsigned CUID = 0) {
+      return getMCDwarfFileTable(CUID).getMCDwarfDirs();
+    }
+
+    bool hasMCLineSections() const {
+      for (const auto &Table : MCDwarfFileTablesCUMap)
+        if (!Table.second.getMCDwarfFiles().empty() || Table.second.getLabel())
+          return true;
+      return false;
     }
     unsigned getDwarfCompileUnitID() {
       return DwarfCompileUnitID;
@@ -325,18 +330,11 @@ namespace llvm {
     void setDwarfCompileUnitID(unsigned CUIndex) {
       DwarfCompileUnitID = CUIndex;
     }
-    const DenseMap<unsigned, MCSymbol *> &getMCLineTableSymbols() const {
-      return MCLineTableSymbols;
-    }
     MCSymbol *getMCLineTableSymbol(unsigned ID) const {
-      DenseMap<unsigned, MCSymbol *>::const_iterator CIter =
-        MCLineTableSymbols.find(ID);
-      if (CIter == MCLineTableSymbols.end())
-        return NULL;
-      return CIter->second;
+      return getMCDwarfFileTable(ID).getLabel();
     }
     void setMCLineTableSymbol(MCSymbol *Sym, unsigned ID) {
-      MCLineTableSymbols[ID] = Sym;
+      getMCDwarfFileTable(ID).setLabel(Sym);
     }
 
     /// setCurrentDwarfLoc - saves the information from the currently parsed

include/llvm/MC/MCDwarf.h

@@ -200,6 +200,11 @@ public:
 };
 
 class MCDwarfFileTable {
+  MCSymbol *Label;
+  SmallVector<StringRef, 3> MCDwarfDirs;
+  SmallVector<MCDwarfFile *, 3> MCDwarfFiles;
+  MCLineSection MCLineSections;
+
 public:
   //
   // This emits the Dwarf file and the line tables for all Compile Units.
@@ -208,7 +213,38 @@ public:
   //
   // This emits the Dwarf file and the line tables for a given Compile Unit.
   //
-  static const MCSymbol *EmitCU(MCStreamer *MCOS, unsigned ID);
+  const MCSymbol *EmitCU(MCStreamer *MCOS) const;
+
+  const SmallVectorImpl<StringRef> &getMCDwarfDirs() const {
+    return MCDwarfDirs;
+  }
+
+  SmallVectorImpl<StringRef> &getMCDwarfDirs() {
+    return MCDwarfDirs;
+  }
+
+  const SmallVectorImpl<MCDwarfFile *> &getMCDwarfFiles() const {
+    return MCDwarfFiles;
+  }
+
+  SmallVectorImpl<MCDwarfFile *> &getMCDwarfFiles() {
+    return MCDwarfFiles;
+  }
+
+  const MCLineSection &getMCLineSections() const {
+    return MCLineSections;
+  }
+  MCLineSection &getMCLineSections() {
+    return MCLineSections;
+  }
+
+  MCSymbol *getLabel() const {
+    return Label;
+  }
+
+  void setLabel(MCSymbol *Label) {
+    this->Label = Label;
+  }
 };
 
 class MCDwarfLineAddr {